With the erection of The Wall, East Germany cut them off from the professional opportunities that existed in the West, and the couple, especially Winfried, had become increasingly disappointed about being unable to cross the border.

As part of their plan, Freudenberg took a job in a public utility that supplied natural gas, and the couple took an apartment in the East Berlin neighborhood of Prenzlauer Berg.

In January and February 1989, they began assembling a 13-metre (43') tall by 11 metre (36') diameter balloon envelope out of polyethylene, which they cut into strips, taped together, and engirded with a string net.

Although East German security had often shot and killed citizens attempting to escape, they decided against shooting because of the possibility of triggering an explosion of the natural gas now leaking.

West Berlin police supposed that Freudenberg climbed the net to cut the envelope, obviously succeeded, and in the ensuing events lost his hold.

[1] After the incident, East German police investigated Freudenberg's friends, family, acquaintances, colleagues, and wife, to determine whether any had participated in the escape attempt.

Because of international attention and pressure over the recent shooting of Chris Gueffroy, the last refugee to be shot by East German border guards, Sabine was given the relatively lenient sentence of three years of probation and then granted amnesty in October 1989.